(i) Field of the Invention
The present invention relates to a cylinder head cover for an internal combustion engine which comprises a composition containing a resin component including a polyamide resin and a modified polyolefin resin, glass fibers and mica and which is excellent in vibration-damping properties in a wide temperature range of from ordinary temperature to high temperature(60.degree.-100.degree. C.) and which has dimensional stability, mechanical strength and heat resistance.
(ii) Description of the Related Art
Recently, in the field of automobiles, there is a noticeable tendency that the cost of fuel is decreased by lightweight design and parts made of resins are employed for cost reduction in place of metal parts.
Above all, a molded article of a glass fiber-reinforced polyamide resin has been used in place of metal parts in the engine compartment such as a cylinder head cover, since this kind of resin article is excellent in mechanical strength and heat resistance.
However, in the molded articles of glass fiber-reinforced polyamide resin in which glass fibers are only blended with a polyamide resin, mechanical properties and heat distortion resistance are improved, but deformation would occur owing to a molding shrinkage difference attributed to the orientation of the glass fibers at the time of molding. In other words, this kind of resin article has the drawback that dimensional stability is poor.
In order to improve the dimensional stability, polyamide resin compositions for engine peripheral parts such as cylinder head cover have been suggested in which glass fibers and an inorganic filler are blended with a specific polyamide resin (Japanese Patent Application Laid-open Nos. 63-168454 and 63-168456). In such polyamide resin compositions, the dimensional stability of the molded articles owing to the deformation at the time of the molding can be improved, but when the molded articles absorb water, their dimensional stability is poor and resistance to antifreeze agents is also poor. In consequence, these kinds of resin compositions are not always satisfactory. As a cylinder head cover for automobiles in which the above-mentioned disadvantages are eliminated, a cylinder head cover for automobiles has been suggested which can be obtained by molding a composition prepared by blending a mixture of a conventional known polyamide resin and a specific high-grade polyamide resin with glass fibers and an inorganic filler (Japanese Patent Application Laid-open No. 63-289063).
However, this cylinder head cover for automobiles is expensive, since a high-grade polyamide resin is used.
In addition, with regard to engine peripheral parts such as a cylinder head cover made of the conventional known composition, the problem of vibration-damping properties which has a noise reduction means is not yet been solved.